package com.singzi.leetcode.niuke;

import java.text.DecimalFormat;
import java.util.Scanner;

public class gougu {
}
class Solution{
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        double a = in.nextInt();
        DecimalFormat df1 = new DecimalFormat("0.000000");
        System.out.println(df1.format(a/(a+1))) ;
    }
}
